多道听觉脑干植入的临床应用

目的 探讨多道听觉脑干植入的手术方法及其对恢复双侧听神经瘤所致全聋患者听力的效果。方法 ７例双侧听神经瘤患者,在肿瘤摘除后将２１道听觉脑干植入（ａｕｄｉｔｏｒｙ ｂｒａｉｎｓｔｅｍ ｉｍｐｌａｎｔ,ＡＢＩ）电极植入于第四脑室外侧陷内,直接刺激脑干耳蜗术休中以面神经电图,舌咽神经肌电图及电诱发听觉脑干反应（ｅｌｅｃｔｒｉｃａｌｌｙ ｃｖｏｋｅｄ ａｕｄｉｔｏｒｙ ｂｒａｉｎｓｔｅｍ ｒｅｓｐｏｎｓｅ     

听觉脑干置入用于双侧听神经瘤全聋患者的听力康复(附1例报告)

目的：探讨听觉脑干置入（ABI）用于双侧听神经瘤全聋患者的听力康复。方法：对1例双侧听神经瘤全聋患者，在经乙状窦枕下径路切除第2侧听神经瘤时，同期将12道听觉脑干装置的电极阵置入第4脑室的侧隐窝内，术中行第Ⅶ、Ⅸ脑神经监测，并且记录电刺激脑干诱发电位，以确定和校正电极位置。术后2个月开通电极并作调试。结果：术后头颅X线侧位片示电极位置正确，术后开通调试发现电刺激12个电极均能引起听觉反应，无一电极引起非听觉反应。结论：多道ABI能让双侧听神经瘤全聋患者产生有意义的听觉。术中电极阵准确地置入到脑干耳蜗核是手术成功的关键。     

神经纤维瘤病II型与听觉脑干植入

目的探讨神经纤维瘤病II型(neurofibromatosis 2,NF-2)(双侧听神经瘤)的临床特征和治疗方法,以及多道听觉脑干植入(auditory brainstem implant,ABI)对双侧听神经瘤切除术后全聋患者听力康复的应用价值。方法回顾性分析了一神经纤维瘤病II型家系3例患者的发病情况和治疗经过。对其中一例患者在经乙状窦后枕下径路切除第二侧听神经瘤时,将12道ABI(MED-EL公司,奥地利)的电极阵置入第四脑室的侧隐窝内,术中行第79、颅神经监测,并结合电刺激脑干诱发电位以校正电极阵位置。术后2月开机并调试。结果文中3例患者早期症状均是以耳部为主,如耳聋、耳鸣、行走不稳感。听觉脑干植入术后开机调试发现电刺激12个电极均能引起听觉反应,无一个引起非听觉反应。结论双侧听神经瘤的临床特点、治疗方法不同于单侧听神经瘤,治疗方案应遵循个体化原则。多导听觉脑干植入能让因双侧听神经瘤导致全聋的患者产生有意义的听觉,术中电极阵准确地植入到脑干耳蜗核是手术成功的关键。对神经纤维瘤病II型患者家庭成员进行筛查有助于该病的早期发现。     

电诱发听觉脑干反应与听觉脑干植入

听觉脑干植入能够使听神经受损耳聋患重新获得听觉。电诱发听觉脑干反应(electrically brainstem response，EABR)测试用于术中定位耳蜗核位置，具有重要作用。电刺激耳蜗核时出现的EABR波形有两种类型：3波反应型和2波反应型，同时可记录到潜伏期较长的肌反应。手术中最佳的EABR测试参数为双相方波脉冲电流、刺激强度3mA、刺激频率50Hz、植入电极板上间距最大的电极做配对刺激、带通滤波10∽3000Hz。EABR作为探讨电听觉整体效果的指标，将在听觉脑干植入研究中发挥重要作用。本就近年来EABR在听觉脑干植入中的应用做一综述。     

电诱发听觉脑干反应与听觉脑干植入

听觉脑干植入能够使听神经受损耳聋患者重新获得听觉.电诱发听觉脑干反应(electrically brainstem response,EABR)测试用于术中定位耳蜗核位置,具有重要作用.电刺激耳蜗核时出现的EABR波形有两种类型3波反应型和2波反应型,同时可记录到潜伏期较长的肌反应.手术中最佳的EABR测试参数为双相方波脉冲电流、刺激强度3mA、刺激频率50Hz、植入电极板上间距最大的电极做配对刺激、带通滤波10～3 000Hz.EABR作为探讨电听觉整体效果的指标,将在听觉脑干植入研究中发挥重要作用.本文就近年来EABR在听觉脑干植入中的应用做一综述.     

听神经病人工耳蜗植入术中EABR监测及其疗效评估

目的:探讨听神经病的病变部位并观察听神经病人工耳蜗植入术后的疗效。方法:选择在我院行人工耳蜗植入术的8例听神经病患者,同时筛选背景接近的8例非听神经病极重度聋人工耳蜗植入患者作为对照组进行配对。回顾性分析2组患者术前听力学资料;术中耳蜗植入前采用自制电极行电刺激听性脑干诱发反应(EABR)评估听觉通路;植入后检测神经反应遥测(NRT)、EABR;并随访术后调机T、C值,采用听觉行为分级标准(CAP)、言语可懂度分级标准、言语识别率评估术前和开机后1年时听力言语情况。结果:8例听神经病患者术中植入前均可引出EABR波形,但是波形较正常有变异,需要刺激量加大或者调整参数,Ⅴ波潜伏期长短不一;植入耳蜗后NRT反应好,EABR和术中测试波形接近。术后开机均有听性反应,随访开机T、C值与对照组差异无统计学意义;听神经病组患者术前及开机1年CAP分别为6.50±0.94和6.90±0.77,言语识别率(双字词)分别为(85.00±11.66)%和(89.50±9.02)%,与对照组比较差异无统计学意义。结论:术前EABR可以做为评估听神经病(听同步不良患者)听觉通路的有效工具,筛选合适植入者;人工耳蜗可以帮助听神经病患者提高听力及言语能力。     

听觉脑干植入

听觉脑干植入(ABI)是人工耳蜗植入技术的一种进展,其工作原理与人工耳蜗类似,不同的是人工耳蜗通过电极刺激耳蜗内的听神经纤维而获得听觉,而ABI是将电极越过耳蜗和听神经直接刺激脑干耳蜗核复合体的听神经元产生听觉.就ABI的适应证及禁忌证、手术入路及手术方法、手术并发症以及植入后听力改善的效果等方面进行概述.     

人工耳蜗植入后EABR动态变化的初步研究

目的观察人工耳蜗植入儿童电诱发听性脑干反应(electrically auditory evoked response EABR)的动态变化,了解慢性电刺激后听觉通路反映特性的变化,为听觉系统的可塑性变化研究提供实验依据。方法本研究采用前瞻性设计,对19例平均年龄为3.2±1.0岁的语前聋儿童在接受人工耳蜗植入术中电极植入后进行EABR检测,患者在人工耳蜗植入后5.4±3.2月后再次进行EABR检测,观察EABR阈值、波III、波V潜伏期以及EABR输入输出曲线指标的变化。结果EABR平均阈值从人工耳蜗植入术中的196.9±11.1CL下降到术后5.4±3.2个月的189.2±13.2CL CL,配对t检验显示显著性差异（p=0.006）。平均阈上20CL V波潜伏期从人工耳蜗植入术中的4.72±0.21ms缩短到术后5.4±3.2月的4.60±0.18ms,配对t检验显示显著性差异（p=0.032）。结论耳聋儿童在接受人工耳蜗电刺激后EABR的反应阈值和潜伏期变化在最初的5.4±3.2月已经出现,提示3岁左右年龄段儿童听觉系统具有较好的可塑性,人工耳蜗植入后早期的听觉、言语训练尤为重要。     

EABR在人工耳蜗植入术前及术中应用研究

人工耳蜗通过在耳蜗鼓阶内植入电极,电刺激耳蜗螺旋神经节使双侧重度或极重度感音神经性聋患者获得或恢复听觉.自House植入第一例人工耳蜗以来,耳鼻喉科医生及听力师开始探索电刺激引发的神经电反应,促进了一系列电生理检查手段的临床应用.NRT以其快速、无需镇静的优势在人工耳蜗植入术后发挥了很大作用,但EABR技术在人工耳蜗植入术前选择、术中检测中仍有广泛的临床应用.近年来,对于特殊病例如听神经病、耳蜗畸形患者的EABR研究己成为热点.     

人工听觉的过去现在和未来

电诱发人工听觉(简称人工听觉)通过电刺激听觉神经来恢复、提高或重建人的听觉功能。电刺激听神经包括早期使用的单电极及目前使用的多电极人工耳蜗植入，以及结合低频残存声听觉的短电极耳蜗植入。人工耳蜗植入的工作原理是绕过已损伤的毛细胞、直接电刺激残存的听神经纤维来达到恢复、重建听觉的目的。也可以将电刺激直接作用于听觉脑干和听觉皮层，适用于听神经发生病变的患者，例如听神经瘤患者。     

Clinical application of the multichannel auditory brainstem implant]

OBJECTIVE: To investigate the surgical techniques and speech performance of multichannel auditory brainstem implant (ABI) in patients with bilateral acoustic neuromas (neurofibromatosis type 2). METHODS: The nucleus 21 channel auditory brainstem implant was implanted into the lateral recess of the fourth ventricle through the translabyrinthine approach in 7 patients after removal of the tumor. The accurate placement of electrode array was ensured by the electromyogram monitoring of the 7th and 9th nerves and the electrically evoked auditory brainstem responses (EABR). Initial switch-on occurred six weeks postoperatively. Speech evaluation was performed every 3 months for the first year and annually thereafter. RESULTS: During the surgery, the lateral recess could be found and the typical EABR could be recorded in 6 cases. They later reported a significant benefit from the device. Two of the cases have achieved functional open-set speech understanding. In contrast, one patient with no EABR because of difficulty of the anatomic location during the surgery had no sensations postoperatively. CONCLUSION: The multichannel ABI could effectively restore auditory sensations in patients deafened by bilateral acoustic neuromas. The accurate location of the cochlear nucleus complex during surgery was the key factor for the success of the operation.     

An auditory brainstem implant system

Neurofibromastosis type II (NF2) is a condition that may result in bilateral acoustic neuromas. The tumors and their removal may cause profound bilateral deafness. Because the auditory nerve is compromised, people with NF2 are unable to receive a cochlear implant to restore a sensation of hearing. Electrical stimulation of the auditory pathway can provide hearing in such people. This is possible by means of an auditory brainstem implant (ABI). This article focuses on the MED-EL high-rate multichannel ABI system. The system consists of the implanted and external components. Appropriate placement of the ABI is dependent on electrical auditory brainstem response testing performed intra-operatively. Data on a group of European patients implanted with the MED-EL ABI are presented. Results are promising and include some open-set speech ability.     

The retrosigmoid approach for auditory brainstem implantation

OBJECTIVE: To describe our experience with the retrosigmoid-transmeatal (RS-TM) approach in auditory brainstem implantation (ABI) as well as the anatomosurgical guidelines for this route. STUDY DESIGN: Retrospective case review. SETTING: Ear, Nose, and Throat Department of the University of Verona. PATIENTS: Five patients with neurofibromatosis type 2 (NF2) were operated on for vestibular schwannoma removal with ABI implantation from April 1997 to June 1999. The patients were four men and one woman, whose ages ranged from 22 to 37 years. The tumor sizes ranged from 12 to 30 mm. The records of a total of 179 patients operated on for vestibular schwannoma (VS) removal via the RS-TM approach from January 1990 to June 1999 were also evaluated. Their ages ranged from 18 to 88 years (average 54 years). The tumor sizes ranged from 4 to 50 mm. Five patients had a solitary VS in the only hearing ear. INTERVENTION: The classic RS-TM approach was used in all patients. After tumor excision, for ABI implantation, the landmarks (seventh, eighth, and ninth cranial nerves, choroid plexus) for the foramen of Luschka were carefully identified. The choroid plexus was then partially removed, and the tela choroidea was divided and bent back. The floor of the lateral recess of the fourth ventricle and the convolution of the dorsal cochlear nucleus became visible. The electrode array was then inserted into the lateral recess and correctly positioned with the aid of electrically evoked auditory brainstem responses (EABRs). MAIN OUTCOME MEASURES: Intraoperative EABR and postoperative speech perception evaluation. RESULTS: Auditory sensations were induced in all patients with various numbers of electrodes. Different pitch sensations could be identified with different electrode stimulation. CONCLUSIONS: In the authors' experience, the RS-TM approach is the route of choice for patients who are candidates for ABI when there is a chance of hearing preservation during surgery. If auditory function is lost during surgery, anatomical preservation of the cochlear nerve may allow hearing restoration with a cochlear implant. Direct intraoperative recording of cochlear nerve action potentials (CNAPs) and round window electrical stimulation are mandatory for these purposes. In addition, decompression of the intrameatal portion of the vestibular schwannoma and planned partial tumor resection with hearing preservation are also possible with the RS-TM approach.     

Nucleus 21-channel auditory brainstem implant in patients with previous tumour removal

Three patients with neurofibromatosis type 2 who had undergone previous cochlear nerve tumour removal were implanted with the Nucleus 21-channel auditory brainstem implant (ABI). The time intervals between tumour removal and implantation were 4, 5, and 7 years, respectively. Total bilateral deafness was confirmed before implantation. One patient was also blind after acute intracranial hypertension. The translabyrinthine approach was used in all cases. The choice of side for implantation depended on pre-operative magnetic resonance imaging study, the facial nerve function, the presence of recurrent and/or other lesions, and the patient's preference. Although the scarring of prior surgical procedure largely changed the anatomical structures in the cerebello-pontine angle, various landmarks could be found to locate the foramen of Luschka, where the ABI electrode was inserted into the lateral recess of the fourth ventricle. During surgery, the electrically evoked auditory brainstem responses were recorded to confirm that the ABI stimulation activated the auditory system; the electromyogram of the 7th and 9th nerves was helpful in finding the landmarks and minimising the triggering of the cranial nerves with ABI stimulation. The number of active electrodes was 21, 7, and 4 in the three patients. All obtained meaningful pitch scaling and useful auditory sensations. One patient, with 21 activated electrodes, has achieved functional open-set speech understanding. The second patient, with 7 activated electrodes, has benefited from environmental sound awareness and improved lipreading. The last, blind, patient, with 4 electrodes activated, achieved only perception of environmental sounds.     

Nucleus 21-Channel Auditory Brainstem Implant in Patients with Previous Tumour Removal: El implante auditivo de tallo cerebral Nucleus de 21 canales en pacientes con reseccion tumoral previa

Three patients with neurofibromatosis type 2 who had undergone previous cochlear nerve tumour removal were implanted with the Nucleus 21-channel auditory brainstem implant (ABI). The time intervals between tumour removal and implantation were 4, 5, and 7 years, respectively. Total bilateral deafness was confirmed before implantation. One patient was also blind after acute intracranial hypertension. The translabyrinthine approach was used in all cases. The choice of side for implantation depended on pre-operative magnetic resonance imaging study, the facial nerve function, the presence of recurrent and/or other lesions, and the patient's preference. Although the scarring of prior surgical procedure largely changed the anatomical structures in the cerebello-pontine angle, various landmarks could be found to locate the foramen of Luschka, where the ABI electrode was inserted into the lateral recess of the fourth ventricle. During surgery, the electrically evoked auditory brainstem responses were recorded to confirm that the ABI stimulation activated the auditory system; the electromyogram of the 7th and 9th nerves was helpful in finding the landmarks and minimising the triggering of the cranial nerves with ABI stimulation. The number of active electrodes was 21, 7, and 4 in the three patients. All obtained meaningful pitch scaling and useful auditory sensations. One patient, with 21 activated electrodes, has achieved functional open-set speech understanding. The second patient, with 7 activated electrodes, has benefited from environmental sound awareness and improved lipreading. The last, blind, patient, with 4 electrodes activated, achieved only perception of environmental sounds.     

Auditory brainstem implantation: The first Indian experience

Multichannel auditory brainstem implants (ABI) are currently indicated for patients with neurofibromatosis type II (NF2) involving both vestibulocochlear nerves. The ABI helps bypass the damaged cochlear nerves and restores a level of auditory sensation via the electrical stimulation of the cochlear nucleus. The implant is usually placed in the lateral recess of the fourth ventricle at the time of tumor resection to stimulate the cochlear nucleus. We report a case of ABI done on a 15-year-old girl with bilateral vestibular schwannomas.     

Central electrical stimulation of the auditory pathway in neurofibromatosis type 2

The auditory brainstem implant (ABI) is a viable treatment option for patients with neurofibromatosis type 2 (NF2) whom either vestibular schwannomas or the surgery used to remove them has rendered totally deaf. This device stimulates the central auditory pathways in a manner similar to the cochlear implant in individuals with a total hearing loss. A multichannel model with transcutaneous signal transmission is in use experimentally in both the United States and Europe. Of 14 patients implanted with the ABI in a European pilot study, 13 received auditory sensations at initial tuning. Surgical implantation of the ABI is generally, but not always, performed at the same time as tumor removal, with the preferred route being the transmastoid-translabyrinthine approach. After insertion, monitoring of the device is required to optimize the location of its electrode on the cochlear nucleus complex.     

The auditory midbrain implant: a new auditory prosthesis for neural deafness-concept and device description.

The auditory midbrain implant (AMI) is a new central auditory prosthesis designed for penetrating stimulation of the human inferior colliculus. The major group of candidates for the AMI consists of neurofibromatosis type 2 (NF2) patients who develop neural deafness because of growth and/or surgical removal of bilateral acoustic neuromas. Because of the absence of a viable auditory nerve, these patients cannot benefit from cochlear implants. An alternative solution has been the auditory brainstem implant (ABI), which stimulates the cochlear nucleus. However, speech perception performance in NF2 ABI patients has been limited. The fact that the ABI is able to produce high levels of speech perception in nontumor patients (with inaccessible cochleae or posttraumatic damage to the cochlear nerve) suggests that limitations in ABI performance in NF2 patients may be associated with cochlear nucleus damage caused by the tumors or the tumor removal process. Thus, stimulation of the auditory midbrain proximal to the damaged cochlear nucleus may be a better alternative for hearing restoration in NF2 patients. We propose the central nucleus of the inferior colliculus (ICC) as the potential site. A penetrating electrode array aligned along the well-defined tonotopic gradient of the ICC should selectively activate different frequency regions, which is an important elementfor supporting good speech understanding. The goal of this article is to present the ICC as an alternative site for an auditory implant for NF2 patients and to describe the design of the first human prototype AMI. Practical considerations for implementation of the AMI will also be discussed.